Carrying bar for a frame in a plate heat exchanger

ABSTRACT

The present invention relates to a plate heat exchanger comprising several heat exchange plates arranged in a frame between a frame plate and a pressure plate, and suspended from a horizontal carrying bar, which has a hollow supporting body with protruding suspension means on its underside for the heat exchange plates. According to the invention the supporting body and the suspension means are formed of a bent sheet material, and the carrying bar has opposite side walls (3, 15, 16) which extend to abutment against each other and are joined to each other at least at lower support surfaces (6) located close to a vertical center plane through the carrying bar, and which beneath said support surfaces (6) extend away from said central plane to form said suspension means.

The present invention relates to a plate heat exchanger comprisingseveral heat exchange plates arranged in a frame between a frame plateand a pressure plate, and suspended from a horizontal carrying bar,which has a hollow supporting body with protruding suspension means onits underside for the heat exchange plates.

Plate heat exchangers of this kind are common and a number of differenttypes of carrying bars have been suggested for them. A previously knowntype of carrying bar is shown for instance in GB 624 865 and isessentially in the form of an I-beam, which is dimensioned withreference to recesses in the heat exchange plates. However, thiscarrying bar has not been sufficiently stiff against torsion inconnection with large plate heat exchangers. Therefore, another type ofcarrying bar has been suggested, which is made of a hollow supportingbody having a rectangular cross section, on the underside of which apart of an I-beam has been welded for carrying of the heat exchangeplates. Carrying bars of both the above mentioned types are mostexpensive to manufacture.

A further type of carrying bar is shown in GB 624 865. Such a carryingbar is made of bent sheet material so that an upper hollow supportingbody is formed, which at the bottom carries suspension means for theheat exchange plates. The suspension means have a width exceeding thatof the supporting body, and consequently this type of carrying barcannot be made too large, if the above mentioned recesses in the heatexchange plates should have reasonable dimensions.

Another problem arises when known carrying bars are used for plate heatexchangers in the food industry. Great demands are made on hygiene, andparts included in the plate heat exchangers must have a surface of acorrosion resistant material. It would be possible to manufacture theknown carrying bars of a corrosions resistant material, but this wouldfurther increase the costs. Instead, up to now one has covered thecarrying bars with a very thin sheet of stainless steel.

The object of the present invention is to provide a carrying bar whichis inexpensive to manufacture irrespective of whether it is made of acorrosion resistant material or some other cheaper material. Thecarrying bar should also be simple to manufacture in different sizes fordifferent plate heat exchangers. Another object is to keep down theweight of the carrying bar.

These objects are achieved with a plate heat exchanger of the initiallydescribed kind which essentially is characterized in that the supportingbody and the suspension means are formed of a bent sheet material andthat the carrying bar has opposite side walls, which extend to abutmentagainst each other and are joined to each other at least at lowersupport surfaces located close to a vertical central plane through thecarrying bar, and which beneath said support surfaces extend away fromsaid central plane to form said suspension means.

By the present invention several advantages are achieved in comparisonwith carrying bars of the known type. On the one hand one starts from asheet material which is being bent to a suitable form, which makes theproposed carrying bar very simple and inexpensive to manufacture, evenif it is formed out of a corrosion resistant material, and on the otherhand both the suspension means and the hollow beam of the carrying barcan easily be adapted to different heat exchange plates and/or todifferent sizes of the plate heat exchanger. The carrying capacity ofthe carrying bar can be varied by changing of the form of the carryingbar and/or by varying of the thickness of the sheet material. Thecarrying bar may of course be made by bending of only one sheet ofmaterial, but it has proved more suitable to make the carrying bar bybending of sheet material into two equal parts which are put togetherand fixed by welding to each other. Thus, within the scope of theinvention it is obtained a great freedom of dimensioning the carryingbar for different existing recesses of different heat exchange plates,and independently of the shape of the recesses, for a required bendingand torsional stiffness.

The invention will be described further below with reference to theaccompanying drawings, in which

FIG. 1 shows a cross section through a carrying bar according to a firstembodiment,

FIG. 2 shows a cross section through one part of the carrying baraccording to FIG. 1,

FIG. 3 shows a cross section through the lower portion of a carrying baraccording to a second embodiment, and

FIG. 4 shows a cross section through the lower portion of a carrying baraccording to a third embodiment.

In FIGS. 1 and 2 there is shown a first embodiment of a carrying baraccording to the invention, which has a hollow supporting body withprotruding suspension means on its underside and which is assembled oftwo parts 1 and 2, which are formed of a bent sheet material, preferablyof stainless steel, and which are fixed against each other. The carryingbar has a length essentially equal to the distance between a frame plateand a pressure plate in a plate heat exchanger, and has opposite sidewalls which extend to abutment against each other close to a verticalcentral plane through the carrying bar. Each part 1 and 2 has a verticalmain portion 3, which continues in an upper horizontal portion 4 havinga horizontal extension which essentially corresponds to half thethickness of the carrying bar. The upper horizontal portion terminatesin an upper support surface 7. The vertical main portion 3, which has asomewhat smaller vertical extension than the thickness of the carryingbar, continues in its lower part in a portion 5 directed obliquelydownwards and which extends essentially as far as the horizontal portionto form a lower support surface 6. Said portion 5 continues in its turnin a portion 8 situated under said support surface 6 and extending awayfrom said central plane. The angle between the portion 8 and the portion5 is within the range of 90°±45° and preferably within the range of90°±20°. The portion 8 thus is directed obliquely downwards and its endportion 9 is essentially between a border line 10 of the verticalportion 3 and a border line between the support surfaces 6 and 7 of thetwo portions 4 and 5. When two parts 1 and 2 are put together, theportions 8 extend in the form of two flanges away from each other andform the suspension means of the carrying bar.

To form a carrying bar one takes two equal plates 1 and 2, one of themhaving been turned halfway around its vertical centre line, and putsthem against each other. Then the plates 1 and 2 will abut against eachother near the vertical central plane through the carrying bar partlyalong a horizontal line corresponding to the contact points between thesupport surfaces 6 of the two portions 5 and partly along a horizontalline corresponding to the contact points between the support surfaces 7of the two portions 4. Along said two lines the plates are fastened toeach other, preferably by means of a welding joint 11 and 12 as shown inthe figure. Instead of welding, soldering, riveting or gluing may beused. Also a screw joint can be used.

The two plate portions 8 of the plates 1 and 2 function, as indicated inFIG. 1, as suspension means for a heat exchange plate 13. Through thespecial design of the portions 8, which extend obliquely downwards andaway from each other, they will abut against the flanks of the dovetailformed groove 14 of a heat exchange plate 13. Hereby the carrying barfunctions perfectly for the most common type of suspension groove of theheat exchange plate.

In FIGS. 3 and 4 there is shown a lower part of a carrying bar accordingto two other embodiments. The carrying bars, as in the embodimentaccording to FIGS. 1 and 2, are made of two equal parts fastened to eachother, and the upper part of the carrying bar corresponds to what hasbeen shown in FIG. 1. However, the lower part of the carrying bars has adifferent design to better fit and cooperate with heat exchange plates,in which the recess for the suspension means of the carrying bar has adesign other than that of a dovetail formed groove.

Common for both embodiments is that the vertical side walls 15 and 16 ofthe carrying bar continue in respective lower horizontal portions 17 and18, each of which is directed towards said central plane, where theseportions meet each other. The lower horizontal portions 17 and 18continue in each respective vertical portions 19 and 20 forming supportsurfaces 6 which abut against each other.

The carrying bar according to FIG. 3 is intended for a heat exchangeplate 23 having a circular recess 24. To fit this kind of recess thelowest portion of the carrying bar is essentially semicircular, thelower vertical portions 19 and 20 of the two parts continuing in arespective portion 25 and 26 formed as a quarter of a circle, which twoportions when put together form a carrying bar, in which a cross sectionthrough the lower part of the carrying bar gets a semicircular form. Theportions 25 and 26 are thus intended to abut against the circular recess26 of the heat exchange plate 23. It is of course possible to modify theportions 25 and 26 so that these together form a circle.

The carrying bar according to FIG. 4 is meant to cooperate with a heatexchange plate 27 having a quadratic or rectangular recess 28. For thispurpose the lowest part of the carrying bar has two horizontalprotrusions 29 and 30 directed away from each other and starting fromtheir respective vertical portions 19 and 20.

I claim:
 1. Plate heat exchanger comprising several heat exchange platesarranged in a frame, between a frame plate and a pressure plate, andsuspended from a horizontal hollow carrying bar having spaced oppositeside walls joined along the upper part of the bar, and having protrudingsuspension means on its under-side for the heat exchange plates, saidside walls and said suspension means being formed of bent sheetmaterial, characterized in that the side walls extend to abutmentagainst each other and are joined to each other at support surfaceslocated at the lower part of the carrying bar close to a verticalcentral plane through the latter, the side walls extending furtherbeneath said support surfaces and away from said central plane to formsaid suspension means, and further characterized in that the carryingbar above said lower support surfaces has a width exceeding the distancebetween the outer ends of said suspension means, and in that saidcarrying bar consists of two equal parts abutting against each other. 2.Plate heat exchanger according to claim 1, characterized in that thelower parts of the side walls form two flanges extending away from eachother.
 3. Plate heat exchanger according to claim 1 or 2, characterizedin that the cross section through each part of the carrying bar has anupper horizontal portion and a vertical main portion, that continuesinto a lower portion directed obliquely downwards, the upper and lowerportions being arranged so that they are directed in the same directionin relation to the vertical main portion.
 4. Plate heat exchangeraccording to claim 3, characterized in that the lower portion of eachcarrying bar continues in an obliquely downwards directed portionforming an angle of 90°±45° with the lower portion, whereby thedownwards directed portions of two parts of the carrying bar abuttingone another form said flanges.
 5. Plate heat exchanger according toclaim 4, characterized in that each part of the carrying bar has anupper support surface and a lower support surface, the respectivesupport surfaces of two abutting against one another parts of thecarrying bar being welded to each other to form the carrying bar. 6.Plate heat exchanger according to claim 1 or 2, characterized in that across section through each part of the carrying bar has an upperhorizontal portion and an upper vertical portion, which latter continuesin a lower horizontal portion directed in the same direction as theupper horizontal portion, and that the lower horizontal portioncontinues in a lower vertical portion, which forms one of said lowersupport surfaces of two parts of the carrying bar abutting one another,which lower support surfaces together with the upper support surfaces atthe ends of the upper horizontal portions are welded to each other forforming the carrying bar.
 7. Plate heat exchanger according to claim 6,characterized in that the lower vertical portion continues in a portionformed as a quarter of a circle which, when two such portions abutagainst each other, form said suspension means for the heat exchangeplate.
 8. Plate heat exchanger according to claim 6, characterized inthat the lower vertical portion continues in a horizontal protrusionwhich, when two such protrusions are arranged against each other, formsaid suspension means for the heat exchange plate.